The Synthesis And Characterization Of Dinitro-pyrazole

Pyrazoles compounds contain the structure of N—N,C—N and C? N bond,theref ore have a high enthalpy of formation,which are the main source of chemical enthal py.Pyrazoles are riched of ? electron,thus have fixed fragrant,may happen electrophil ic substitution reaction in pyrazole-heterocuclic.Prazoles have some excellent properties such as low noxious,efficient and secure,consequently the synthesize of pyrazoles c ompounds is also a hotspot in green chemistry,can be used in medicine,farm chemic al and organic intermediate.Nitropyrazoles compounds get much attention due to the c haracters in itself.In this paper,N-Nitropyrazole,3-Nitropyrazole,1,3-Dinitropyrazole,3,5-Dinitropyra zole and 3,4-Dinitropyrazole were prepared via steps:nitration and rearrangement,usin g pyrazole as a raw material.Nitropyrazole is the important intermediate product in p yrazole nitration,single-factor test and orthogonal design experiment are carried out to build a route and study on N-Nitropyrazole,3-Nitropyrazole,1,3-Dinitropyrazole and 3,5-Dinitropyrazole.The major research results are as follows:(1)N-Nitropyrazole,3-Nitropyrazole,1,3-Dinitropyrazole and 3,5-Dinitropyrazole were synthesized by nitration,rearrangement,nitration and rearrangement using pyrazole.Experiment results show that the temperature on the N-Nitropyrazole yield has the greatest impact in N-Nitropyrazole synthesis experiments.The optimum reaction temperature is 15 ?,The optimum reaction time is two hours.In 3-Nitropyrazole synthesis experiments,the best reflow media is benzonitrile and the reflow temperature is160 ?.Dinitration reaction conditions determined for the material ratio of 1:2.2(mol),the optimum temperature is under 0?,the best reaction time is 2.5 hours.The optimum temperature is 140 ? in 3,5-Dinitropyrazole synthesis experiments.All above the purity was above 95%.(2)Design and synthesis of 3,4-Dinitropyrazole.(3)IR,UV,liquid chromatography,and melting point test were used to characterize five kinds of nitropyrazoles.(3)UV-visible spectroscopy of purified nitropyrazoles,comparison with pyrazole:The introduction of the nitrate group will cause the energy of the pyrazole ring conjugated system increased.Nitropyrazoles in the ultraviolet region of the K,B,the R band which are the energy of the pyrazole ring conjugated system in the ?-?? electronic transition absorption.Contrast to the literature,the measurement has distance with the calculated value.There is a certain deviation in theoretical values.(4)Explore a system of two mixed acid nitration the nitrification basic principle and the active nitrating agent according to pyrazole nitration reaction mechanism.Compare the nitrification capacity of the active nitrating agent.The advantages and disadvantages of the HNO3-Ac2O-AcOH nitrification system and HNO3-H2SO4 nitrification system are summarized.